Optical splitters are power dividers that produce “N” number of replica signals by splitting the power of the input optical signal N times. For example, a 1×2 optical splitter divides a single optical signal input into two optical signal outputs, each with half the power of the input signal. These optical splitters, however, also exhibit an additional power loss, called the excess loss, which is caused by the power inefficiency of the splitter. In the previous example of the 1×2 optical splitter, if the splitter is 99% efficient, the two optical output signals would have 49.5%, instead of 50%, of the power of the input optical signal. An example of this type of power splitting is shown in FIG. 1, where the PL is the excess power loss of the optical splitter.
The power loss resulting from processing these optical signals in optical splitters has a significant impact on the configuration of a telecommunications network. For example, a Cable TeleVision (CATV) network could have a transmitter outputting 5 dBm of power, and use receivers with input power sensitivities of −25 dBm. To minimize the number of transmitters, the CATV signal provider could divide the output of a transmitter with optical splitters to serve as many subscribers (receivers) as possible. The resulting signal distribution network could be implemented as shown in FIG. 2, where the optical signal from the transmitter 20 is split by the optical splitter 22 at the transmitter site, routed to remote distribution hubs 24, split again in optical splitters 26, and routed to the subscribers 28.
If the various optical splitters are 1×16 units with 1 dB of excess loss, then the optical splitters would introduce 26 dB of loss into the network. Because the power budget of this example is only 30 dB (5−(−25)), only 4 dB of power would remain for other network losses, such as fiber and connector loss, and link margin. For this example, the optical splitter loss has reduced the transmitter availability to 256 subscribers located within approximately 6 km of the transmitter. If the optical splitters did not exhibit the split loss, then the only loss incurred in the network would be caused by fiber attenuation and connectors. This low loss would allow the number and location of subscribers served by the transmitter to be increased to values limited by other than technical factors for the CATV operator.